The growing but limited success of school-based health-risk prevention programs has been due to multiple session, multiple booster in-class presentations where all students receive the intervention together. Recent developments suggest that the most effective programs are not delivered by the regular in-class teacher and that differential treatment effects may be produced, depending on whether the student is 'at risk" for developing substance abuse or other health risky patterns. That is, providing high impact programs which are targeted toward "at risk" students may result in iatrogenic effects in those who are not at risk or are at low risk for developing these tendencies. The proposed four year project is a model preadolescent substance abuse and AIDS-risky behavior prevention program, implemented within an urban school system, designed to 1) screen high risk students based on teacher-rated and self-report behavioral disinhibition/impulsivity, a characteristic predictive of early onset health-risky behaviors; 2) provide an in-class high impact, 10 session, 2 booster, skills-based program delivered by specially trained student teachers from a local university; 3) integrate resources from three universities, a local urban school system and a private consulting firm for the purposes of program implementation and evaluation. The design of this project draws on theoretical and empirical contributions from social learning theory (Bandura, 1977) McGuire's (1961) theory of attitude inoculation, Botvin's (Botvin et al., 1984) life skills training, and problem behavior theory(Jessor & Jessor, 1977). In year one, specially trained student teachers from a local university will present out ten session AIDS and substance abuse high impact prevention program to three different pre-identified groups of high risk and low risk students. Three student teachers will be assigned to each treatment intervention classroom, with each teacher presenting the same high impact program to one of the previously screened risk groups. Regular in-class health/physical education teachers will provide the state mandated AIDS and substance abuse prevention program to the comparison group. Booster sessions will be provided for the treatment intervention group during years 2 & 3. A pretest and nine posttest measures of attitudes, knowledge and behaviors related to AIDS-risky behavior and substance use will be used as outcome measures. Teacher and student process measures will be used as part of the planned quantitative and qualitative evaluation.